Hydroxytelechelic natural rubber from natural rubber and epoxidised natural rubber
2011
Thitithammawong, A. | Srangkhum, S. | Rungvichaniwat, A.
Hydroxytelechelic natural rubber (HTNR), a chemically modified form of natural rubber which can be used as a polyol precursor in the elaboration of natural rubber based polyurethane was synthesised. In this study, the effects of different types of starting materials including natural rubber (NR) and epoxidised natural rubber (ENR) on properties of HTNR were explored. Two steps of controlled methodology were applied. The first oxidative degradation step using periodic acid yielded carbonyltelechelic natural rubbers (CTNRs) having similar chemical structures as proven by 1H-NMR and FTIR analysis. However, they were different in carbonyl content, percent yield and molecular weight, as well as in appearance. The results suggest different degradation mechanisms occurring in NR and ENR. The HTNRs were later prepared in a second step by reduction of the CTNRs with sodium borohydride followed by hydrolysis with cool water. Using the ENR-based CTNR as intermediate in the second step provided the HTNR with hydroxyl content, percent yield, OH-value higher than that using the NR-based CTNR, whereas molecular weight and acid number were lower. These meant that the ENR was more suitable than NR to be selected for production of HTNR.
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